The Prince of Wales told a schoolboy it "was really fun being a grandfather" to Prince George, who was born on Monday afternoon.
Charles met George Austin, nine, as he opened a new garden at Kemble railway station in Gloucestershire, two days after he met his grandson for the first time.
George and sister Lucinda, four, were at the station - the closest to the Prince's Highgrove home - with their grandparents.
George, who lives in Wimbledon, south west London, said: "I was asking him about the baby and he said it was great meeting him at the hospital.
"He said it was really fun being a grandfather."
The latest addition to the royal family has been named Prince George Alexander Louis, but where did the Prince get his names?
The Duke and Duchess of Cambridge have named their son George Alexander Louis, Kensington Palace said.